Image forming apparatus

Abstract

Disclosed is an image forming apparatus including an image forming unit which forms a toner image on an image carrier and transfers the formed toner image on a paper, a color conversion process unit to carry out a color conversion process to convert inputted image data to image data of an output color in the image forming unit, a paper type information obtaining unit to obtain at least one or more information among a size of a paper, a basis weight of the paper and whether the paper is coated or not and a control unit to control so as to change a maximum adhesion amount of a toner to a paper by selecting a color conversion process condition for the color conversion process unit based on the information obtained by the paper type information obtaining unit.

What is claimed is: 
     
       1. An image forming apparatus, comprising:
 an image forming unit which forms a toner image on an image carrier and transfers the formed toner image on a paper; 
 a color conversion process unit to carry out a color conversion process to convert inputted image data to image data of an output color in the image forming unit; and 
 a control unit to make the color conversion process unit carry out a preparatory color conversion process to the inputted image data, to determine whether a pixel value of each pixel constituting image data after the preparatory color conversion process is greater than or equal to a threshold which is predetermined or not, to detect the number of pixels in which the pixel value is greater than or equal to the threshold, to select a color conversion process condition for the color conversion process unit based on the detected number of pixels in which the pixel value is greater than or equal to the threshold, and to make the color conversion process unit carry out an actual color conversion process to the inputted image data according to the selected color conversion process condition. 
 
     
     
       2. The image forming apparatus of  claim 1 , wherein the control unit selects the color conversion process condition which makes the pixel value of each pixel constituting the image data after the color conversion process by the color conversion process unit be small as the number of pixels in which the pixel value is greater than or equal to the threshold is greater. 
     
     
       3. The image forming apparatus of  claim 1 , wherein the threshold is different for each of areas which are made by dividing an image generated by the image data after the color conversion process by the color conversion process unit in a plurality of areas. 
     
     
       4. The image forming apparatus of  claim 3 , wherein the threshold is smaller in an area corresponding to a top of the paper among the plurality of areas comparing to other areas. 
     
     
       5. The image forming apparatus of  claim 1 , wherein a selecting of the color conversion process condition for the color conversion process unit by the control unit is a selecting of a three dimensional look-up table to be used in the color conversion process in the color conversion process unit. 
     
     
       6. The image forming apparatus of  claim 1 , wherein the output color in the image forming unit includes yellow, magenta, cyan and black, and
 the control unit selects the color conversion process condition for the color conversion process unit so as to set a maximum adhesion amount of a black toner to a constant and so as to change a maximum adhesion amount of a toner of yellow, magenta and cyan. 
 
     
     
       7. The image forming apparatus of  claim 1 , wherein the output color in the image forming unit includes yellow, magenta, cyan and black, and
 the control unit selects the color conversion process condition for the color conversion process unit so as to set a maximum adhesion amount of a toner of yellow, magenta and cyan to a constant and so as to change a maximum adhesion amount of a black toner. 
 
     
     
       8. An image forming apparatus, comprising:
 an image forming unit which forms a toner image on an image carrier and transfers the formed toner image on a paper; 
 a color conversion process unit to carry out a color conversion process to convert inputted image data to image data of an output color in the image forming unit; and 
 a control unit to make the color conversion process unit carry out a preparatory color conversion process to the inputted image data, to determine whether a color of each pixel constituting image data after the preparatory color conversion process fulfills a determination condition which is predetermined or not, to detect the number of pixels which fulfill the determination condition, to select a color conversion process condition for the color conversion process unit based on the detected number of pixels which fulfill the determination condition, and to make the color conversion process unit carry out an actual color conversion process to the inputted image data according to the selected color conversion process condition. 
 
     
     
       9. The image forming apparatus of  claim 8 , wherein a selecting of the color conversion process condition for the color conversion process unit by the control unit is a selecting of a three dimensional look-up table to be used in the color conversion process in the color conversion process unit. 
     
     
       10. The image forming apparatus of  claim 8 , wherein the output color in the image forming unit includes yellow, magenta, cyan and black, and
 the control unit selects the color conversion process condition for the color conversion process unit so as to set a maximum adhesion amount of a black toner to a constant and so as to change a maximum adhesion amount a toner yellow, magenta and cyan. 
 
     
     
       11. The image forming apparatus of  claim 8 , wherein the output color in the image forming unit includes yellow, magenta, cyan and black, and
 the control unit selects the color conversion process condition for the color conversion process unit so as to set a maximum adhesion amount of a toner of yellow, magenta and cyan to a constant and so as to change a maximum adhesion amount of a toner of black.